Group B streptococcal breast abscess in a mother and mastitis in her infant.

Group B streptococcus is a common cause of postpartum infection, but breast abscess in a lactating woman has not been reported. Seven days postpartum, a woman developed mastitis resulting from type Ib/c group B streptococcus. She was treated with oral antibiotics for 1 week, with apparent resolution. Breast-feeding was continued, but at reduced frequency on the affected side. Two days later, local and systemic symptoms recurred, and a large breast abscess was surgically drained. Five days into the mother's initial episode of mastitis, her infant developed type Ib/c group B streptococcal mastitis, requiring hospitalization and parenteral antibiotic therapy. It is likely that the pathogenesis of infection in this mother-infant pair was circular, and that either early abscess formation during the mother's first clinical infection and/or milk stasis due to decreased frequency of breast-feeding resulted in transient group B streptococcal bacteremia, with seeding of breast tissue in the newborn.